Given a filename, open() and mmap() it as the data field of a Buf.

Tag the Buf with 'mmaped' boolean to make sure free_buf knows
to munmap rather than xfree the data structure, and so we can
call fatal_abort if xfer_buf_data or grow_buf are called.

Documented, and code reads as needing, the node lock. But these
were incorrectly set as the job locks.

Bug 5394.

Needs the job write lock, as it may change job status not just node
status. Especially after commit 33e352a6.

Bug 5406.

harden some gres related tests

An is_*() named function should return true/false, but not modify things.
It has been renamed to a more adequate name: remove_path_slashes(char *).

Bug 4859

Previously, slashes '\' in job->cwd were always expanded regardless of they
were part of the name of a directory or not.

Bug 4859

When dealing with special characters like %A, %u, %s and so on and escaping it
on the command line, problems arises when one have directories with multiple
slashes in their names. This patch fixes this situation removing only one
slash on each pair of slashes just as normal escaping works i.e. in bash.

Bug 4859

Bug 5426.

Previously, usage was just CPU-seconds. However, since
TresBillingWeights has been added, usage gets calculated from that, or
it's just CPU-seconds if TresBillingWeights isn't defined.

Bug 5434.

Bug 5426.

Also remove some redundant logic

Add errno to info message in the SlurmDBD log, and pass the actual
errno back to the sacctmgr process so the user can see it.

Bug 5152.

- avoid `abort()` when collective is failed
- added logging of coll details for fail cases

Bug 5067